This invention relates to an electromagnetic flowmeter capable of accurately measuring the flow rate of a fluid passing through a circular conduit even when the fluid does not fill the conduit but has a free surface.
In conventional electromagnetic flowmeters which utilize a voltage induced between a pair of point electrodes located opposite each other on the wall of a measuring tube as a flow rate signal, it is assumed that the flowing fluid fully fills the tube, and the meter readings are not valid or accurate when the tube is only partially filled, i.e. when the fluid has a free surface.